Learn about this topic in these articles:

parasitic attack on plants

Abnormal root growth is revealed by comparison with healthy roots. Some nematodes, such as root knot (
Meloidogyne species), produce small to large galls in roots; other species cause affected roots to become discoloured, stubby, excessively branched, and decayed. Bacterial and fungal root rots commonly follow feeding by nematodes, insects, and rodents.

Root-knot nematodes (
Meloidogyne species) are well known because of the conspicuous “knots,” or gall-like swellings, they induce on roots. More than 2,000 kinds of higher plants are subject to their attack. Losses are often heavy, especially in warm regions with long growing seasons. Certain species, however, such as the northern
root-knot nematode (
M. hapla), are...